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(c) Sindre Torp
The photo is of a "home brew" unit built in a 2-BQ speaker cabinet. These were built by testers on the production line and by technicians in the service department.
We primarily used Heathkit test equipment when possible, it was good equipment and a reasonable investment. The vacuum tube voltmeter of choice was the Heathkit model IMW-11. We used the standard DC probe and also the RF probe. To use the RF probe the standard DC probe had to be removed and the RF probe inserted into the front panel jack or vice versa.
The "home brew" unit eliminated the need to constantly change probes. The two jacks along the bottom and on each side of the two slide switches allowed both probes to be inserted at the same time. The selector switch, with the 4-line knob, allowed the user to select the desired probe. When the tester was not using the voltmeter, the switch was in the ALC position and the ALC of the transmitter being tested was monitored.
The unit in the photo is a little more elaborate than most of the "home brew" boxes I made or remember. All of the boxes had the 2-BQ speaker, as the Jensen speaker was excellent. The unit in this photo has a slide switch to select the internal speaker or a load resistor. It was probably used as a "mute" switch.
The W-4 wattmeter movement was simply used as the indicator, not as a wattmeter. It was probably in the ALC line, but may have been in the audio line.
I assume the jack labeled "SCOPE" was to connect to a scope, but I'm not sure why, perhaps to look at the audio. The slide switch, on the left, was probably used with the "IN" jack and the "EXT", but I'm not sure. I'm sure the technician, that built this unit, had a function in mind. We were allowed to build what ever would help us get the job done, within reason of course.
Bill Frost
02/15/2005
